An animal whose retina has no cone cells probably cannot:

• A. See at all
• B. Distinguish color
• C. See 3D objects
• D. Distinguish shades of black and white

Answer: (B)

Color vision relies on cone cells. If the retina has no cones, the animal loses the ability to tell colors because there’s no mechanism to distinguish different wavelengths as color differences. Rods, which are still present, keep vision in low light and detect brightness differences, so shapes, movement, and light-dark contrasts can still be seen, just not in color. Depth and 3D perception can often be inferred from cues other than color, such as shading and perspective, so that ability isn’t eliminated by the absence of cones. Distinguishing shades of black and white is still possible based on light intensity, even without color information. Therefore, the missing color distinction is the aspect that would be lost.